1. Field of the Invention
The present invention relates to novel crystalline and amorphous forms of naltrexone methobromide. The invention also encompasses related processes, compositions, and methods.
2. Background of the Invention
Naltrexone methobromide is an opioid antagonist. The compound and methods for the synthesis of naltrexone methobromide are described in U.S. Pat. No. 4,176,186 and WO 2004/043964. Naltrexone methobromide (CAS: 73232-52-7) has the molecular formula C21H26BrNO4 and the following structural formula:

There is a need for new crystalline forms of naltrexone methobromide. The discovery of new crystalline forms of a pharmaceutical compound provides an opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for designing, for example, a pharmaceutical dosage form of a drug with a targeted release profile or other desirable characteristic.
WO 2004/108084 discloses polymorph forms of naltrexone base, however, naltrexone base and naltrexone methobromide are different molecular species and therefore do not possess the same solid-state properties.
All documents cited herein, including the foregoing, are incorporated by reference in their entireties for all purposes.